alpha-Tocomonoenol Is Bioavailable in Mice and May Partly Be Regulated by the Function of the Hepatic alpha-Tocopherol Transfer Protein

Tocomonoenols are vitamin E derivatives present in foods with a single double bond at carbon 11' in the sidechain. The alpha-tocopherol transfer protein (TTP) is required for the maintenance of normal alpha-tocopherol (alpha T) concentrations. Its role in the tissue distribution of alpha-11 '-tocomonoenol (alpha T-1) is unknown. We investigated the tissue distribution of alpha T-1 and alpha T in wild-type (TTP+/+) and TTP knockout (TTP-/-) mice fed diets with either alpha T or alpha T-1 for two weeks. alpha T-1 was only found in blood, not tissues. alpha T concentrations in TTP+/+ mice were in the order of adipose tissue > brain > heart > spleen > lungs > kidneys > small intestine > liver. Loss of TTP function depleted alpha T in all tissues. alpha T-1, contrary to alpha T, was still present in the blood of TTP-/- mice (16% of alpha T-1 in TTP+/+). Autoclaving and storage at room temperature reduced alpha T and alpha T-1 in experimental diets. In conclusion, alpha T-1 is bioavailable, reaches the blood in mice, and may not entirely depend on TTP function for secretion into the systemic circulation. However, due to instability of the test compounds in the experimental diets, further in vivo experiments are required to clarify the role of TTP in alpha T-1 secretion. Future research should consider compound stability during autoclaving of rodent feed.